MXPA97003462A - Magnetic articles conformable for the use of consumption that support traf - Google Patents

Abstract

The magnetic conformable articles (100) are described for use with traffic-supporting surfaces, which comprise an organic binder (4) having magnetic particles (6) distributed therethrough. The articles can be used in intelligent systems for vehicle guidance, and in systems for guiding other mobile objects such as farm animals, pets, or pedestrians with visual problems. The methods for the elaboration of the articles and the methods for using the systems to control and / or guide a moving object are also described, using the magnetic field generated from the articles

Description

MAGNETIC ARTICLES CONFORMABLE FOR USE WITH SURFACES THAT SUPPORT TRAFFIC BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of magnetic articles, in particular, to articles that can be applied to a road, store floor, and the like, for guiding a vehicle or other moving object thereon. 2. Related Technique The safest, most efficient and most accessible transit for citizens is a high priority for many governments. Public service workers, public transit vehicles and emergency vehicles must have the ability to move more quickly and safely on roads in a variety of environmental conditions. The inclement weather and even the blinding solar light or the traffic light to come, present special problems for the existence of REF: 2462 travel systems and for guidance systems that offer collateral control to vehicles. An unfortunate number of tragic accidents have occurred due to people driving under the influence of alcohol and prohibited drugs. A magnetic lateral guidance system addresses the special needs of drivers who can not, for whatever reason, see the road. Snowy conditions, fog, heavy rain, scattered dust and smoke are examples of challenges for vehicle drivers. The snowy climate presents particularly challenging driving conditions for snow removal drivers trying to clear the streets when the snow blows, or when road markers are obstructed by snow. In addition, the reduced visibility imposed by blowing snow has caused numerous tragic accidents when car drivers have rear end snow that makes them travel slower than the traffic that surrounds them. The winter weather will continue to be a challenge to any intelligent transport system (ITS) in which vehicles move at faster speeds and closer together on more crowded roads.

A magnetic system offers several advantages: - it is not adversely affected by environmental conditions; - does not require expensive video or other radio frequency equipment; - the operating costs of the system remain low since the marker is passive - no energy is required to perform a magnetic marker function; - the durability of the system means that, once installed, a magnetic marker will likely last beyond the life of the road (roads typically have lives of six to eight years) and can even be reprogrammed while still on the road; and - removable magnetic markers offer the convenience of being able to remove the marker from the road and "reprogram" it. Various alternative methods to detect the lateral position of a vehicle on a road have been suggested. One option involves the use of visible signs or markings and optical sensors. A system that relies on optical sensors can be expected to have reliability problems. Signs or markings may be obscured by dust, ice, or snow, and visibility may be impaired by fog, blowing snow, flying dust, and the like. In addition, for night use, a considerable amount of energy must be spent, either to illuminate the signs or to send a beam from the sensor. Another procedure is the use of radar reflector markers with a radar telemetry system on the vehicle. Markers and radar detection systems are expensive compared to the magnetic system proposed here. Metallic radar reflector markers embedded in the road are likely to have durability and corrosion problems. Two known magnetic marking systems deserve attention. One proposal is to use a series of magnetic "nails" embedded in the road. Because the resistance in the field decreases as the cube of distance from such a source of dipolar magnetic field, the "nails" would have to be closely spaced to produce a useful signal. Installation costs could be high, as this requires drilling holes in the road, and material costs could be very high if more powerful rare earth magnets are used, to minimize size and maximize spacing. The drilling of holes in the road can also lead to stress concentration and premature failure of the pavement (road surface), which can be exacerbated by the corrosion of the nails. The use of simple spikes of ferrous metal could not provide the desirable alternating signal to effectively separate the position signal from the noise. Another magnetic marking system uses a magnetic paint to produce magnetic strips on the road. With the typical thickness of the paint layers, it would be difficult to obtain a good magnetic signal. If the thickness of the paint was constituted to obtain a good magnetic signal, its durability would be poor. The paint strip could be magnetized only after it has dried. The specially designed magnetization accessory would have to be carried along the strip. Due to the limitations in the magnetic field produced by such an accessory, the coercivity of the magnetic material would have to be limited to approximately 1,000 users, making it susceptible to erasure, and it could be difficult to produce anything other than a longitudinal magnetization pattern. Conventional, non-magnetic, conformable pavement marking sheet materials typically comprise a polymeric material, such as one that could be cross-linked to form an elastomer, but which is not crosslinked in the sheet material and thereby provides the desired viscoelastic properties. A mixture of this material with other non-magnetic inorganic fillers and inorganic fillers has been found to provide properties that give long-lasting pavement markings, which have good ability to conform to a road surface, abrasion resistance, resistance to traction and breaking. The composition may have glass spheres embedded in its upper surface for retroreflective purposes. An example of this type of pavement marking is described in U.S. Patent No. 4,490,432. In summary, these advantages can be obtained with a composition comprising 100 parts of non-crosslinked elastomer precursor; at least 5 parts of a thermoplastic reinforcing polymer (such as a polyolefin) which is dispersed in the elastomer as a separate phase (for example, due to insolubility or immiscibility with the other polymeric ingredients) and softens at a temperature of approximately 75 ° C and 200 ° C; a particulate inorganic filler dispersed in the composition; and preferably an extender resin, such as a halogenated paraffin. This composition is processable in calendering rollers to form a thin sheet material, and generally between about 3 millimeters thick. The nature of separate phases of the reinforcing polymer is considered desirable, since it is believed that the polymer becomes oriented during the calendering operation and reinforces the sheet material. Such reinforcement is indicated by the fact that the tensile strength of the sheet material is significantly stronger in the downward direction of the net (for example in the calendering direction) than in the cross direction of the net or transverse. U.S. Patent No. 5,316,406 discloses a strip similar to marker rubber for road, in which the top layer is deformed into protuberances such as wedges or ridges, preferably provided with a coating of exposed retroreflective spheres, which have been crosslinked-vulcanized to provide it with memory that allows the restoration of the shape after the depression by vehicle traffic, and an inner layer not vulcanized, cold flow, adhered to the road and that conforms with the memory to the same low vehicle traffic. Other non-magnetic, conformable pavement markings are described in U.S. Patent No. 4,069,281 (Eigenmann), in Italian Patent Application No. MI 003213 / 91A (which discloses a conformable layer comprising a saturated acrylonitrile-butadiene elastomer. grafted with a salt of zinc or methacrylic acid), and European Patent Application No. 93.911016.9, which describes a conformable butadiene layer and at least one resin selected from the group consisting of hydrogenated polycyclodiene resins and hydrocarbon resins aliphatic Another method for pavement markings has recognized that the ability to shape the marking for pavement to the pavement can be improved by using a conformable base layer on which retroreflective elements are placed, either by incrustation or by the use of a binder layer. In an article, described in U.S. Patent No. 5,194,113, the shaping layer comprises a ductile thermoplastic polymer (preferably a polyolefin) and a non-reinforcing mineral particulate. Yet another article, described in U.S. Patent No. 5,120,154, employs a base layer comprising a microporous thermoplastic polymer characterized by exhibiting certain non-elastic properties of deformation / conformability. In none of the above descriptions the use of magnetic particles is described or suggested. Magnetic installations on roads and methods for providing control information for vehicles traveling on roads are described in, for example, U.S. Patent No. 3,609,678. This patent relates to the useful magnetic materials based on polymers, which are elastic to make the elastic and flexible material, such as nitrile and silicone rubbers, and PVC (polyvinyl chloride) plasticized. Magnetic items are embedded in the road either transversely to the flow of traffic or in the direction of traffic flow. This patent also describes "wrong track" control systems and systems for controlling the speed and course of vehicles traveling on the road. None of the known articles or known systems describes or suggests a conformable magnetic article, or suggest a need for such an item. In addition to vehicles, other moving objects such as farm animals, pets, fire controllers, visually impaired pedestrians, and the like could also benefit from control and / or guidance systems comprising conformable magnetic articles. Mobile robots equipped with magnetic sensors could be guided and / or controlled as they move on their track, for example, along an industrial assembly line. Perimeter warning systems and limits are necessary in specific instances. Two examples include warning of hazardous conditions in the environment and pet containment systems. Games often require defined limits, such as the territory of fouls in baseball and off limits in football, and it is often desired that toys and sports equipment emit audible signals.

BRIEF DESCRIPTION OF THE INVENTION The conformable magnetic articles of the present invention, and the systems within which they are incorporated, show a number of advantages over the previous procedures, either non-magnetic and magnetic. Its reliability in all weather conditions must be much better than that of optical systems. The cost of manufacturing and installing the preferred items (magnetic pavement marking tapes, conformable, or "CMPMT") is low in relation to other procedures. With the set of modern integrated circuits, the cost of the detector and the associated signal processing is modest, and very little energy could be required for the operation. A magnetic material with excellent environmental stability is used, and the durability must be comparable to that of existing pavement marking tapes, which have already been tested in the field. The magnetization could be done in a factory; on the site immediately before or after the installation of the articles, or much later in time after the installation of the articles ("rewritable" or "reprogrammable"), with relatively simple equipment. Materials with coercivities of up to 20,000 persons can be used, making the articles of the invention highly resistant to accidental or deliberate erasure. Thus, one aspect of the invention is a conformable magnetic article (preferably in the form of a sheet) comprising: a) an organic binder (preferably comprising materials selected from the group consisting of non-crosslinked elastomeric precursors, thermoplastic polymers (more preferably ductile thermoplastic polymers), and combinations thereof); and b) a plurality of magnetic particles distributed in the organic binder, the magnetic particles being able to remain remotely magnetized and present in an amount sufficient to produce a magnetic field sufficient to be detected by a sensor (either one or more, depending on the particular application), and the guidance and / or control of a moving object that moves relative to the article. As defined herein, the term "mobile object" includes vehicles controlled by humans; humans involved in a variety of activities; farm animals; pets; fire controllers; mobile robots, and the like, all equipped with magnetic sensors having the ability to detect a magnetic signal or signals from conformable magnetic articles of the invention, and converted that signal or signals to an audible, tactile, visual or other warning signal and / or control. In a particularly preferred embodiment the articles of the invention comprise a plurality of magnetic particles distributed within a conformable layer of a marking tape for conventional pavement. Preferably, the magnetic particles are physically oriented to increase the remaining magnetization in a preferred direction. The articles of the invention are preferably magnetized in a regular alternating pattern, to produce an alternating magnetic signal, easily detectable, on the sensor. However, to transfer more varied information, the articles of the invention can be magnetized ("coded" or "written") into more complicated patterns, as found in bar codes, on credit card strips, or recordings on magnetic tape. The conformable, magnetic articles of the invention (preferably in the form of adhesive-reinforced tapes) preferably comprise a conformable magnetic layer containing permanently magnetizable particles, such that the magnetic particles of the article can be oriented to produce a magnetic field that is detectable by a sensor mounted on a vehicle, typically mounted 15-30 cm (6 to 12 inches) above the road. The articles of the invention preferably produce a magnetic field of at least 10 milligaus at a lateral displacement from the midline of the article of up to 61 cm (24 inches). In the tests described in the Examples section herein, it was surprisingly found that one embodiment of the articles of the invention produced a magnetic field of at least 10 milligaus at a lateral displacement of approximately 2 meters (m) from the line intermediate of the article of the invention. The typical width of the articles is in the range of about 1 cm to 50 cm, preferably 5 to 20 cm, and the typical thickness of the article is in the range of about 0.1 cm to about 1.0 cm, preferably from about 0.1 to 0.2. cm, although many other forms of the article are possible, with the form dictated mainly by the specific use of the article. When controlling / guiding vehicles, the articles of the invention may be either placed on the road surface, or placed in a ditch on the road. In the latter embodiment, if the surface is a "fresh" asphalt surface (for example still hot), or uncured concrete mix, freshly deposited, the articles of the invention can be placed initially on top of the fresh asphalt or of the uncured concrete, and thereafter pushed down substantially at a level with the surface using any suitable means such as a roller. Still another aspect of the invention are the methods for making the articles of the invention. An inventive method comprises the steps of: a) the combination of an organic binder precursor with a plurality of magnetic particles, the magnetic particles being capable of being permanently magnetized and present in an amount sufficient to produce a magnetic field, sufficient to be detected by a sensor and guide a vehicle that moves relative to said article; and b) exposing the binder precursor to conditions sufficient to form a conformable organic binder having the magnetic particles dispersed therein. Preferably, the product of step b) is further exposed to conditions sufficient to orient the magnetic particles in a desired direction, to produce the desired magnetic field (such as exposure to a permanent magnet or electromagnet). Alternatively, the orientation step may be before step b) of exposure. The term "binder precursor" means an organic material that has not been processed to the final organic binder. Examples of "exposing the binder precursor to conditions sufficient to form a conformable organic binder" include cooling in the case of a molten thermoplastic polymer; exposure to an energy source, such as radiation by particles (eg, electron beam) and non-particle radiation (eg, ultraviolet or visible light), exposure to heat in the case of the binder precursor of thermosetting, and similar. In some embodiments of organic binder, for example when the organic binder comprises non-crosslinked elastomeric precursors, traditional methods for rubber processing are preferably used to produce the conformable magnetic layer. Typically and preferably the composition is made in some kind of heavy-duty, batch or continuous kneader, such as a Banbury mixer or twin screw extruder. The conformable magnetic layer can be formed by calendering between heavy rollers, and then divided to the desired width, directly by extrusion through a die, or by a combination of such methods. If the extruded material is semiliquid as it leaves the die, the desired magnetic orientation of the magnetic particles can be produced by exposure to a permanent magnet or electromagnet at the outlet of the die. If the extruded material is more rubber-like than liquid, magnetic orientation using electromagnets can not be successful, but magnetic orientation can often be achieved by mechanical work. Plate-like particles, such as barium hexaferrite, will respond to mechanical work by orienting with their planes in the plane of the sheet. Since the preferred magnetic direction for such particles is perpendicular to the plane, the preferred magnetization direction of such an article will be perpendicular. The needle-like particles will tend to align with their longitudinal axis in the plane. Since the magnetic easy axis (sometimes also referred to as the "preferred axis" by those skilled in the magnetic arts, both meaning the direction of magnetization of a particle in the absence of an external magnetic field) corresponds to the axis of the needle, the preferred direction of magnetization for an article containing such particles, is transverse or longitudinal. The flow of extension, such as occurs during extrusion, will promote longitudinal orientation at the expense of the transversal. Other embodiments of articles of the invention, for example those having: separate and conformable magnetic layers; uncrosslinked or vulcanized, separate forming layers, and vulcanized or crosslinked cold flow layers; security layers (which can increase, up to twice the strength of the magnetic field); anti-skid and / or retroreflective layers; and the like, can be made by employing lamination steps, with adhesives that are optional between the layers, as described more fully in relation to each specific article embodiment with the present. Yet another aspect of the invention is a control and / or warning system for moving objects, comprising: a) at least one conformable magnetic article of the invention, the magnetic particles are capable of being remotely magnetized and presented in a sufficient quantity to produce a magnetic field sufficient to be detected by a sensor and to guide a moving object that moves relative to the article; b) a sensor that detects the magnetic field produced by the magnetic article; and c) an indicator (preferably an electronic indicator, for example a visual component, such as a cathode ray tube (CRT) or liquid crystal display (LCD), or an audible component such as a "horn") which receives a signal In some system modes, such as toys, the sensor and the indicator are effectively the same item, for example when the sensor is a pair of metal strips that are pulled together in a rapid manner in the presence of a magnetic field To emit a ticking sound, the mobile object is preferably a vehicle, such as a snowplow operated by a human, a passenger vehicle, a truck or the like, In a preferred embodiment of the vehicle control system, a magneto-sensing Resistive is coupled to the underside of a vehicle, such that it is approximately 30.5 cm (12 inches) above the ground surface. The invention may be of a variety of sizes; a preferred size is 5.1 x 5.1 x .6 cm (2 x 2 x 3 inches). The output signals or signals from the sensor are transmitted to a visual display unit or screen, preferably by means of an electrical cable, although optical and radio frequency means could also be used. The display unit is typically placed within the driver's view. Exemplary system embodiments include a microprocessor, preferably located within the display unit, to perform the signal processing required to convert the output signals of the sensors to a lateral position shift signal. In an open back side guidance system, this signal is then used to trigger an indicator (screen, meter, horn and similar) to be used by the driver in the manual adjustment of the vehicle's position. In a closed-loop control system, the signal is used to drive a controller that exerts an influence on the vehicle, such as speed of adjustment, steering and the like. Note that signal processing, while previously described as occurring within the display unit, could alternatively be performed within the sensor unit by moving the microprocessor to that site. If this is done, the output of the sensor unit (s) could be a side shift signal, and the function of the display unit could only be to convert a signal to a shape appropriate to the needs of the driver. Note also that a microprocessor is not required, that is, the signal processing could be performed using analog electronic devices, for example, operational amplifiers, trigonometric function generators, and the like. A method of control and / or guidance of a moving object using a magnetic conformable article, of the invention, as a component of a system of the invention, which is another aspect of the invention. The lateral control of vehicles, especially those that operate on busy highways, requires great precision and accuracy. A key technical step to design a lateral vehicle control system is to define the procedure to obtain a position of precision of the vehicle, fixed relative to the edge or center of the road. The hardware and computer hardware customary for the sensor (such as read-only memory (ROM)) is preferably used to mathematically convert the signal from the conformable magnetic articles of the invention (via the sensor) to a shift position. side of the vehicle on the road. The sensor uses electronic control and visual representation devices to detect and indicate the position of the vehicle to the driver of the vehicle. A device and method useful in the present invention for determining the interval and the relationship in a plane of. an object characterized by a magnetic dipole is described in U.S. Patent No. 4,600,883 (Egli et al.). This patent describes the mathematics required to derive the lateral position, based on the strength of the components of the magnetic field. Mathematics can be reduced to practice by means of the commercially available software (software), such as a fluctuation sheet program that runs on a microprocessor. An advantage of the magnetic conformable articles of the invention lies in the fact that, by appropriate processing of the signal, the magnetic field produced by the articles of the invention and measured by one or more sensors coupled to a moving object, it can be converted to a signal indicating the position of the moving object. In the systems of the invention that signal is preferably used as a visual and / or audio indicator for the mobile object and / or as an input signal for an automatic control system designed to keep the mobile object in a fixed position, such like in a lane on a highway. An example of a visual indicator could be a gauge on the dashboard of a snow plow vehicle, showing the snowplow operator how far to the right or left was the operator from the center of the lane to be cleaned (or how close to the edge it is). of the lane). An example of an audio signal could be an audible alarm that could light up next to the driver of a truck when the truck began to deviate from the road, over the shoulder, possibly as a result the driver of the truck will go to sleep. The automatic control system can function as a component of an intelligent vehicle system (IVS) in which vehicles are automatically controlled to move in fixed lanes at fixed speeds and spacings, such as in an intelligent highway vehicle system (IVHS) or the intelligent transportation system (ITS). This magnetic system offers cost advantage over procedures based on optical procedures, and can also be functional when the optical systems are incapacitated, such as during inclement weather. By magnetizing the strip in a more complicated pattern, additional information can be encoded. For example, information regarding the direction and radius of a curve to come on the road or with respect to the slope of an approaching ascent or descent, could be used for feedback control of the lateral position and position of the vehicle . As part of a vehicle navigation system, location codes could be given. Additional aspects and advantages of the invention will become apparent from the figures of the drawings, the description of the preferred embodiments, the examples and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1-7 are cross-sectional (enlarged) views of seven different embodiments of the conformable magnetic articles according to the invention; and Figure 8 is a schematic diagram of an inventive control and / or guidance system, according to the invention (absent magnetic conformable article). Figures 1-7 are idealized and not to scale. It is intended that all figures are illustrative and not limiting.

DESCRIPTION OF THE PREFERRED MODALITIES I. Modalities of the conformable Magnetic Article The articles of the invention may comprise a series of layers, with each layer having a separate function, but it should be understood that this is not necessarily the most preferred configuration. All the different layers of the magnetic and conformation layers (which are preferably in one layer) are optional. In effective practice, it is desirable to simplify the structure by combining several of the functions in a single layer. From the top to the bottom, the layers of an article within the invention having multiple layers, each have a separate function, as follows: i) Appearance / durability / traction layer. This layer is chosen to give the articles the desired appearance, such as a highly visible traffic lane marking, and to have sufficient durability, to protect the layers below it. It is also possible to provide a surface mixture that improves the traction of the tires in contact with the layer, and can reduce skidding. This layer can be continuous or discontinuous across the driving surface of the article's traffic. ii) Magnetic layer. This layer contains the permanently magnetizable material in an organic binder, both of which are described more fully herein. iii) Security Layer This layer, if used, could be a thin sheet (1-100 microns) of a highly magnetic permeable material, such as zinc-coated or tin-coated steel. With a perpendicular magnetization pattern, this can increase (up to double) the effective thickness of the magnetic layer. iv) Conformation layer. This layer is characterized by a high degree of conformation to the underlying road or other surface and a high proportion of viscous damping to the elasticity. Such a layer promotes and contributes to the improved adhesion of the article of the invention to the underlying surface, in response to the driving of vehicles or repeated walks on it. This layer can alternatively be placed above the magnetic layer. The shaping layer may also comprise two sublayers, an upper elastic layer and a lower inelastic cold flow layer, such as described in U.S. Patent No. 5,316,406. v) Adhesive layer. This layer, which may be a chemical adhesive (such as a pressure sensitive, heat sensitive adhesive, hot melt thermoplastic, or contact adhesive) or a mechanical adhesive (such as a pair of entangled sheets, one of which is attached to the road, the other to the bottom of the article) allows the coupling of the article to the road. Figures 1-7 illustrate in transverse (enlarged) sectional views seven non-limiting embodiments of the conformable magnetic articles according to the present invention. Figure 1 illustrates the conformable magnetic article 100, comprising a layer of polymeric binder 4 having dispersed therein a plurality of magnetic particles 6, magnetically steerable. The combination of the organic binder 4 and the magnetic particles 6 is referred to herein as the magnetic layer 2. Preferably, the conformable magnetic articles of the present invention are conformable, magnetic pavement tapes having an adhesive 8 on the main surface bottom of the article, as described in Figure 1. Without or a layer of adhesive 8 is used, article 100 can be secured to the road by other means, such as mechanical clamps, plastic nails, or other fasteners such as interlocking articles. described in U.S. Patent No. 5,344,177. Figure 2 represents the conformable magnetic article of Figure 1, having a liner or liner layer 10 temporarily adhered to the adhesive layer 8, with the conformable magnetic article 200 having the same magnetic layer 2 as the modality 100 in the Figure 1. Figure 3 represents an alternative magnetic pavement marking tape within the invention, again showing the magnetic layer 2 comprising the binder 4, magnetic particles 6 and the adhesive layer 8. The mode 300 of the Figure 3 also illustrates an anti-skid retroreflective layer, comprised of a vinyl, epoxy, acid olefin copolymer or elastic polyurethane backing layer 12, which serves to adhere transparent microspheres 14 and irregularly shaped skid resistant particles 16 to the layer 2. In the illustrated embodiment 300, the transparent microspheres 14 serve as retroreflective elements. The construction of the mode 300 is generally that described in the US patents Nos. 4,117,192 and 5,194,113, except for the presence of magnetic particles 6 in the magnetic layer 2, and other inventive characteristics therein, such as the volume loading of the magnetic particles. As described in U.S. Patent No. 4,117,192, the support layer 12 is less thick but generally less inelastic than the magnetic layer 2. Thus, despite the deformable inelastic nature of the magnetic layer underlying the layer support, and despite the very thin nature of the support layer, the support layer does not cancel out the desired inelastic deformation properties of the magnetic layer, which represent superior durability, and the support layer nevertheless supports the microspheres in the Top of the article In exemplary embodiments the thickness of the magnetic layer 2 is at least about one millimeter, more preferably at least about one millimeter, but preferably less than three millimeters. The support layer 12 adhered to the magnetic layer 2 is generally more elastic than the magnetic layer 2, which means that after the application and after the deliberation of the deforming tension, it returns more closely to its original shape than the magnetic layer 2. The result of this when the microspheres are pressed at normal ambient temperature in a sample of support layer 12 placed on a hard underlying surface with a pressure that could embed the microspheres in the magnetic layer 2, the microspheres are not reached to embed but remain on the surface of the support layer 12 after the pressure has been released. In addition, the support layer 12 has good adhesion to the retroreflective elements or other particulate material to be embedded therein, which helps to maintain such particles against penetration into the magnetic layer, and possibly the orientation of the magnetic particles 6 in the magnetic layer. an unwanted address. Vinyl-based polymers (polymers including at least 50% by weight of polymerized vinyl monomer units) are especially useful materials for layer 12 due to their toughness, abrasion resistance, and durability in a highway environment. The support layers based on vinyl polymer are typically plasticized to provide the desired flexibility. The backing layer 12 may or may not be pigmented to provide color to the article, and the magnetic layer is typically pigmented in a different color to provide color continuity after the backing layer has been eventually removed by traffic abrasion. . Other aspects of mode 300 of Figure 3 are described in general (except for magnetic particles 6) in U.S. Patent No. 4,117,192. Figure 4 illustrates an enlarged cross-sectional view of the mode 400, which is a conformable, removable, preferred magnetic pavement marking tape according to the present invention. Markings for pavement of this nature are described in general in the North American papal No. 4,299,874 (except for the inventive aspects herein). Mode 400 is essentially identical to that of mode 300 of Figure 3, except that adhesive layer 18 comprises a woven or non-woven fibrous web 21, embedded therein and impregnated by the adhesive layer. A layer 20 of the adhesive layer illustrated in Figure 4, as placed between the magnetic layer 2 and the fibrous web 21, and another layer 22 of adhesive, is placed on the side of the opposite network from the magnetic layer 2, to form the outer bottom surface of the tape of the invention, although there is no requirement that any adhesive be between the network 21 and the magnetic layer 2. As with the embodiments of Figures 1 and 2, a lining material or Coating (not shown) can be included on the adhesive layer 18 opposite the magnetic layer 2. The fibrous web is preferably embedded in the adhesive layer and is sufficiently porous, and the fibers are sufficiently separated so that the adhesive can saturate, for example, surrounding the individual fibers of the network. Typically and preferably, the fibers are separated on average by less than 1 millimeter. Optionally, random fibrous networks may include continuous reinforcing strands in the longitudinal and transverse directions, such as some of the fibrous networks known under the trade designation BAYEX, available from BAYEX, Incorporated, of Albion, New York. A useful fibrous network is that known under the trade designation BAYEX XP483, which comprises two nonwoven webs of 14.7 g (0.5 ounces), sandwiched on both sides of a material consisting of 1000 denier PET mesh yarn, being the individual thread strands spaced 5.84 cm (2.3 inches). When a fibrous web is embedded in the adhesive layer, at least a majority proportion of the adhesive is removed from the road after removal of the tape. However, good removal of the adhesive can also be achieved if the fibrous network is embedded in the magnetic layer 2 (or an intermediate conformation layer of the layer 2 and the adhesive layer 18) instead of being in the adhesive, for example , by impregnation of the network with a polymeric material and magnetic particles, to leave a magnetic layer above the network in which the microspheres can be embedded. These articles of the invention are preferably easily removed, so that they can be run through a machine to recode or replace a section of the article. In some embodiments, the fibrous web should be sufficiently stretchable so that it could be at least stretched 20 percent and preferably at least 50 percent before rupture in all directions. If a fibrous web having longitudinal and transverse reinforcement is used, such as those known under the trade designation BAYEX, the directional conformation is obtained, for example, the articles are not stretched generally longitudinally but diagonally around the projections on the way. Preferred fibrous webs comprise polyester filaments fused together, which has good durability and weather resistance; the polyester of fused filaments is a product in the form of a sheet of continuous filament polyester fibers that are randomly arranged, highly dispersed and joined at the junctions of the filaments. The curly fiber forms, which offer higher elongation and lower residual strength after elongation, they are especially preferred. Other non-woven sheets of randomly distributed fibers and other varieties of polymeric fibers (for example, polyolefins and acrylics) are also useful. In all the described forms of the 400 embodiment, the fibers are distributed so that the fibers extend in a plurality of directions (except for any continuous strands present), which contributes to a multidirectional breakthrough resistance, which improves the capacity of the fibers. retirement. As measured by the trapezoidal breaking strength test (ASTM D1117, paragraph 14; a test specimen is marked with a trapezoid that has a height of 75 millimeters and parallel lateral dimensions (base and top) of 100 and 25 millimeters; the sides not parallel to the specimen are clamped in the jaws of the extraction test machine, and a continually increasing load is applied, in such a way that the tear or rupture propagates through the specimen; the measured absolute force is considered as the trapezoidal breaking resistance, in the present), the network should have a resistance of at least 2 and preferably at least 5 kilograms / centimeter of width in any direction, to provide resistance to nicks and Other cuts that the sheet material may experience on the road, and which may cause breakage of the article during road removal. The tape mode 400, with the fibrous web present, has a tensile strength of at least 0.5 kilograms per centimeter in width, and preferably at least 1 kilogram per centimeter in width. Despite the good tensile strength, the residual strength shown by all the articles of the invention must be low to allow it to remain in good conformation to the irregularities of a paved surface. This residual force is typically described as creep recovery in the penetration mode, as will be explained later herein. Although the residual force properties just described characterize the 400 mode of the article, preferably the reinforcing network itself shows such properties, independently of the other parts of the article 400. In the preparation of the articles of the invention, which include a fibrous network in a layer of adhesive, the fibrous network is typically impregnated with a liquid version of the adhesive (100% solids or less) for example by passing the network through a knife coater. Sufficient adhesive can be applied to the reinforcing network in this manner, so that it can adhere to a magnetic layer; or the magnetic layer can be covered with a layer of adhesive before the application of the impregnated network, and the aggregate adhesive can be applied to form the lower portion of the adhesive layer. Figure 5 illustrates an enlarged cross-sectional view of a portion of an alternative mode to that of mode 300 of Figure 3. Mode 500 of Figure 5 is characterized by having conformable layer 24 between magnetic layer 2 and layer elastic 12. A construction such as this can be made by laminating with a suitable adhesive, a conformable, conventional marking tape for pavement, such as that known under the trade designation STAMARK (permanent) or SCOTCHLANE (removable) (both available from Minnesota Mining and Manufacturing Company ("3M") of Saint Paul, Minnesota), each of which could include layers 24 and 12, to a magnetic layer 2. An adhesive layer 8 can then be applied by any of a number of methods such as roller coating, knife coating, spray coating , and similar. Figure 6 illustrates an enlarged cross-sectional view of the modality 600, which is a modality of marking for magnetic pavement, alternative within the invention. Microspheres 14 having a refractive index of about 1.5 to 2.0 are shown embedded (approximately 20 to 80%) in layer 24 on top of the protuberances, and fully embedded in layer 24 in the valleys between the protuberances. The magnetic particles 6 are present in the layer 24 as in the other embodiments of the invention. Such an article (and method of construction) are generally described in U.S. Patent No. 4,388,359 (except for the features of the invention herein.) The base layer 24 is deformable to allow etching, generally under heat and pressure. protuberances are generally at least one millimeter in height, with approximately one millimeter spacing.The side surfaces must form an angle to the plane of the base sheet of at least 30 °, preferably 60 °, for maximum retroreflection. Figure 7 illustrates mode 700, which is similar to mode 600 of Figure 6, except that the reflecting spheres are adhered only on the side surfaces and on a small portion of the upper surface of the protuberances, using an organic binder. , such as a thermoplastic or thermosetting "spherical bonding" material.A binder of this type is a thermoplastic resin based on vinyl that includes a white pigment, as described in U.S. Patent No. 4,117,192. Other suitable spherical bonding materials include two-part polyurethanes, formed by the reaction of polycaprolactone diols and triols with hexamethylene diisocyanate derivatives; epoxy-based resins described in U.S. Patent Nos. 4,248,932; 3,436,359; and 3,580,887; and block polyurethane compositions as described in U.S. Patent No. 4,530,859. Also suitable spherical bonding materials are polyurethane compositions comprised of a moisture activated curing agent and a polyisocyanate prepolymer. The moisture activated curing agent is preferably an oxazolidine ring. Such compositions are described in U.S. Patent No. 4,381,388. The construction details of the article 700 are further explained (except for the features of the invention herein) in U.S. Patent Nos. 4,988,555 and 4,988,541.

II. Binding Materials for Conformable Magnetic Layers The magnetic layer must be capable of being remotely magnetized, and is preferably conformable to the surface to which the article is applied.

A. Conformation Capacity Test.

The desired properties of shaping a material can be indicated by a penetration creep recovery test, as generally explained in U.S. Patent No. 5,127,973 (Sengupta). In this test, which is based on isothermal thermomechanical analysis, a probe is placed in contact with a sample of the material to be tested, a load placed on the probe, and the penetration of the probe into the verified sample. After a while, the charge is removed from the probe and the position of the probe is checked periodically as the sample is allowed to recover. The test is typically carried out in a helium atmosphere using a thermomechanical analyzer module controlled by a temperature programmer, such as a Perkin Elmer TMS-1 thermomechanical analyzer, controlled by a Perkin Elmer DSC-2 temperature programmer. The mounting of the penetration probe in flat point is used, with the specified diameter of the tip of the probe (typically 1 millimeter with Perkin Elmer equipment). Samples of the materials to be tested are prepared to have a uniform sample thickness of approximately 0.8 millimeters and area dimensions of approximately 3 millimeters by 3 millimeters. The cut sample is transferred to a small aluminum drum and placed on the sample platform of the thermomechanical analyzer. The load of one gram is placed on the probe and the probe is released and dropped on the sample. After approximately 3 to 5 seconds of contact with the sample, the load of one gram is removed and the sample is allowed to relax. This results in the tip of the probe resting on the sample in a zero load condition. The temperature control chamber of the thermomechanical analyzer is raised to surround the sample platform and bring the sample to thermal equilibrium at the desired temperature of the test (generally from about room temperature to 30 ° C, which is the typical temperature for roads during the installation of sheet material of the invention). The sample is allowed to equilibrate at the test temperature for approximately five minutes with the probe still in contact with the sample surface in a zero load condition. The acquisition of data from the position of the probe is then started, with the probe still under a load of zero, to establish the baseline at zero load. After a short time, approximately 20 seconds, a mass of 20 grams is placed on the probe, and the deviation of the probe as it penetrates into the sample is checked periodically. The load is allowed to remain on the sample for two minutes, after which the 20 gram mass is removed from the probe to again reach a zero load condition for the recovery step of the test. The recovery of the sample is checked periodically for at least another two minutes. The penetration amount two minutes after the load was applied and the recovery percentage two minutes after the load is removed, are measured from the traces of the creep recovery data obtained in the experiment. In a test as described, it has been found that for layers with useful shaping ability, a probe having a diameter of 1 millimeter generally penetrates at least 0.05 millimeter, and preferably penetrates at least 0.08 millimeter. Such penetration values indicate that the layer will achieve the necessary conformability under the application pressure used to apply the sheet material and under the typical subsequent pressures from vehicles traveling on the road. The top layer in some embodiments of the article of the invention is preferably hard (such as the pavement marker used at the intersections, as described in U.S. Patent No. 5,127,973), and suffers a penetration of less than 0.05 millimeter in the test described. On the other hand, to minimize the elastic recovery that could be released by the sheet material of the road, the formable layer should recover after the removal of the load, not more than 65 percent of the distance at which the probe has penetrated, and preferably not more than 50 percent of the distance penetrated. When used, the conformable layer is generally thick enough, so that the material of the layer can flow into cracks or fissures in the surface to which it is applied, and develop contact with a large portion of the surface irregular full. In general, the conformable layer must be at least a quarter of a millimeter thick, and preferably it is at least half a millimeter thick. Consistent with the conformability properties discussed above, the conformable layer is preferably a stretchable or flowable material. For example, the conformable layer is preferably capable of being stretched at least 50 percent prior to breaking at a tension rate of 0.05 second "1 for a 1 cm wide sample.As a simpler test, and with experience, someone of experience in pavement marking technique can in general determine whether a particular sample of a material in the form of layers, for shaping, will show the desired characteristics of creep recovery simply by handling the sample and probing it with a Such "manual" characteristics are frequently used in day-to-day testing, and it is the method used in the examples section.

B. Non-crosslinked elastomers.

The non-recovered elastomer precursors are a conformable, preferred, organic binder material used in the articles of the invention, as described in U.S. Patent No. 4,490,432. Such viscoelastic materials allow the absorption of the forces and pressures of traffic on wheels on the roads, without the creation of internal forces that tend to remove the marking of the road. "Elastomeric precursor" is used herein to describe a polymer which can be cross-linked, vulcanized or cured to form an elastomer. "Elastomer" is used to mean a material that can be stretched, at least about two times its original dimensions without rupture, and after the release of the stretching force it quickly returns to its substantially original dimensions. Acrylonitrile-butadiene polymers are especially desirable elastomeric precursors because they offer a high degree of oil resistance. Other elastomeric, non-crosslinked, useful precursors which offer good oil resistance include neoprene and polyacrylates. The polymers of natural rubber and styrene-butadiene can also be used. Extender resins, preferably halogenated polymers such as chlorinated paraffins, but also hydrocarbon resins, polystyrenes or polycyclodienes, are preferably included with the precursor ingredients of the non-crosslinked elastomer, and are miscible with, or form a simple phase with, the ingredients of the elastomeric precursor. The extender resins preferably represent at least 20 percent of the organic components in a conformable layer when this binder is used. To achieve the desired mixing of a thermoplastic reinforcing polymer and the other ingredients in such a system, the reinforcing polymer must be softened at a temperature between about 75 ° C and 200 ° C. Useful thermoplastic reinforcing polymers include polyolefins, vinyl copolymers, polyethers, polyacrylates, styrene-acrylonitrile copolymers, polyesters, polyurethanes and cellulose derivatives. To achieve the desired reinforcement, the polymer must be generally extrudable as a continuous, stretchable, self-supporting film, which is typified by low density polyethylenes having molecular weights of 75,000-100,000 or more, low linear polyethylenes. density and high density polyethylenes having molecular weights of 20,000 or more. At least 5 parts of the thermoplastic reinforcing polymer: but generally not more than 100 parts are included per 100 parts of the uncrosslinked elastomer precursor, and preferably between about 10 and 50 parts are included. The proportions may be varied within the established ranges, depending on the amount of other ingredients included in the composition, especially the amount and type of magnetic and non-magnetic fillers included.

C. Other Binders.

In other embodiments of the preferred article of the invention, the shaping layer has two primary components: a ductile thermoplastic polymer and a non-magnetic, non-reinforcing mineral particulate. Preferably, the thermoplastic polymer is a polyolefin. These binders are generally described in U.S. Patent No. 5,194,113. Suitable polyolefins for use in those binders include polyethylene, polypropylene, polybutylene, and copolymers of those materials. Preferably, the polyolefin is a polyethylene or a linear polyethylene copolymer prepared in part from propylene, butene, hexene, or octene monomer. More preferably, the polyethylene is an ultra low density polyethylene (ULDPE). Ultra-low density polyethylene means linear ethylene copolymers with densities no greater than 0.915 g / cmJ. The melt index of the appropriate polymers is no greater than 300 g / 10 minutes by the method 1238-79 of ASTM. The melt index of the most preferred polymer components of the composite material, it should be less than about 20 g / 10 minutes as measured by the ASTM D1238 method. ULDPE formed as an ethylene-octene copolymer with from about 3-8 mole percent octene is preferred, and about 5 percent mole octene is more particularly preferred. For example, Attane 4001 brand ULDPE; Attane 4002 brand ULDPE; and Attane 4004 ULDPE brand, available from Dow Chemical Company of Midland Michigan, are appropriate components. The densities of such polyethylenes are in the range of about 0.880-0.915 g / m3, with a melt index in the range of 1.0 g / 10 minutes and 3.3 g / 10 minutes, and are thought to contain about 4.5 percent mol of octene. The density of a polymer is indicative of the crystallinity in the bulk copolymer. For ethylene copolymers with different comonomers of α-olefins (for example, ethylene vinyl acetate or ethylene-acrylic acid copolymers) a polymer of a given crystallinity would have a density different from that of polyethylene of the same crystallinity. Therefore, when selecting or predicting the suitability of such polymers, it is more appropriate to consider their crystallinity rather than their densities. Another preferred embodiment of the articles of the invention may use a conformation layer comprising microporous thermoplastic polymer, which forms articles characterized by showing, when tested using the standard tensile strength test apparatus, at least 25% of non-elastic deformation (ID) after being stretched once at 115% of the length of the original sample. In a broader sense, a base sheet characterized by at least 25% ID may be used after being stretched to 115% of its original length in the sheet construction, although the entire article may show less ID. The upper surface is useful as a printed sign or marker, for example, when colored or reflectorized. As used herein, the term "thermoplastic polymer" refers to conventional polymers, either crystalline or non-crystalline, which are processable under ordinary melting conditions and ultra-high molecular weight grades of such polymers, which are not ordinarily intended. that are processable in molten form. The term "melting temperature" refers to the temperature at which a crystalline thermoplastic polymer in admixture with compatible liquid will melt. The term microporous means that it has diluent phase or a gas such as air throughout the material in the pores or empty spaces of microscopic size (for example, visible under a microscope but not with the naked eye). Although pores do not need to be interconnected, they can be. The typical pore size in the microporous base sheet of this class of articles of the invention is in the range of 100 Angstroms to 4 microns. The term "crystalline", as applied herein to thermoplastic polymers, includes polymers that are at least partially crystalline or semi-crystalline. Crystallizable polymers are those which, after cooling from a melt under controlled conditions, spontaneously form geometrically regular and ordered chemical structures, and crystalline polymers are those that have such structures, indicated by X-ray diffraction analysis and a Different peak in analysis by differential scanning calorimetry (DSC). The crystallization temperature means the temperature at which a polymer will crystallize in the molten mixture of the thermoplastic polymer and the compatible liquid. The term "solid diluent" means a material that is a solvent in the process of making the microporous polymer, but which is solid at room temperature, about 24 ° C. Such solid diluents can remain in the finished base sheet. A gel is a material comprising a dispersed component (the thermoplastic polymer in the case of this disclosure) which is a high molecular weight polymer, and the dispersing medium (the solvent or diluent) which is, on average, more molecular weight low. Both components are geometrically continuous throughout the volume of the material, forming the polymer phase a continuous three-dimensional network; while, the diluent fills the remaining volume within the network. The gels show mechanical properties characteristic of solids and not liquid characteristics: the measurable modulus of elasticity, which is usually very low for the polymer in question; and a relatively low elastic limit. The thermoplastic polymers useful in this type of conformation layer in the embodiments of the invention, include polyamides, polyesters, polyurethanes, polycarbonates, polyolefins, diene-containing polymer (vinylidene fluoride), poly (tetrafluoroethylene), and polyvinyl-containing polymers. Representative polyolefins include high and low density polyethylene, ethylene-propylene-diene terpolymers, polypropylene, polybutylene, ethylene copolymers, and polymethylpentene. The polyethylene is understood herein to mean any ethylene polymer that may also contain minor amounts (eg not more than 5 percent mole) of one or more other alkanes copolymerized therewith, such as propylene, butylene, pentene, hexene, 4- methylpentene and octene. Mixtures of thermoplastic polymers can also be used. HMWPE (high molecular weight polyethylene), for purposes of this description, has a molecular weight of 100,000 to 1,000,000, preferably 200,000 to 500,000. UHMWPE (ultra high molecular weight polyethylene) has a molecular weight of at least 500,000 preferably at least 1,000,000. The thermoplastic polymer may include, mixed therein, certain conventional magnetic additive materials, in a limited amount so as not to interfere with the portion of the microporous base sheet or the orientation of the magnetic particles, if magnetic particles are included in this type of magnetic particle. conformation layer. Such non-magnetic additives may include colorants, plasticizers, ultraviolet radiation stabilizers, fillers and nucleating agents. Non-magnetic fillers in polymers are generally known, and some examples are: silicates (such as clay, talc or mica); or oxides (such as A1203, MgO, Si02 or Ti02). Nucleation agents according to U.S. Patent No. 4,726,989 can be used as a raw material. Examples of nucleating agents are dibenzylidene sorbitol, titanium dioxide, adipic acid, and benzoic acid. In making the porous base sheet, the thermoplastic polymer is mixed with a compatible organic diluent, for example, a diluent which will not degrade the polymer and with which the thermoplastic polymer is at least partially miscible. The diluent will dissolve at least a substantial fraction of the polymer at the melt processing temperature of the thermoplastic polymer, but will separate the polymer phase or the cooling phase at a temperature below the melting or crystallization temperature. The diluents can usually be liquid or solid at ambient conditions (approximately 25 ° C). The liquid diluents preferably have a relatively high boiling point at atmospheric pressure, at least as high as the processing temperature in molten form of the thermoplastic polymer, preferably at least 20 ° C higher. The compatibility of a liquid diluent with a given thermoplastic polymer can be determined by heating the polymer and the liquid diluent to form a clear homogenous solution. If such a solution can not be formed at any concentration, then the liquid is not compatible with the polymer. For non-polar polymers, non-polar organic liquids with similar solubility parameters at room temperature are generally useful. Polar organic liquids are generally useful with polar polymers. Some diluents useful with polyolefins are: aliphatic or aromatic hydrocarbons such as toluene, xylene, naphthalene, butylbenzene, p-cumene, diethylenebenzene, pentylbenzene, monochlorobenzene, nonane, decane, undecane, dodecane, kerosine, tetralin or decalin. Some representative mixtures of thermoplastic polymer and liquid diluent useful in the preparation of the microporous thermoplastic polymer are mixtures of polypropylene and mineral oil, dibenzyl ether, dibutyl phthalate, dioctyl phthalate or mineral alcohol.; polyethylene and xylene, decalin, decanoic acid, oleic acid, decyl alcohol, mineral oil or mineral spirits; polypropylene-polyethylene copolymer and mineral oil; polyethylene and diethyl phthalate, dioctyl phthalate or methyl nonyl ketone. The relative amounts of the thermoplastic polymer and the diluent will vary with each system. The mixture of the thermoplastic polymer and diluent may comprise about 1 to 75 weight percent of thermoplastic polymer. For HMWPE, it is preferred to use from about 20 to about 65 percent by weight (more preferably from about 30 to about 50 percent by weight) of polymer in the diluent, and for UHMWPE, it is preferred to use less than 30 percent by weight of polymer, more preferably less than 20 percent by weight. The nucleating agent may be present in a proportion of 0.1 to 5 parts by weight per 100 parts of polymer. In general, solid diluents can be selected from any material (which meets the definition of solid solvent and the criteria for diluents above) with which the thermoplastic polymer is compatible at elevated temperature. If the solid solvent is to remain in the base sheet, it must be flexible and deformable when it is emptied as a film or sheet at room temperature. For polyethylene, such materials may include, but are not limited to, low molecular weight polymers and resins; for example, that they have a sufficiently low molecular weight, so that the polymeric diluent is substantially miscible with a polyethylene melt. Examples of useful solid solvents are petroleum microcrystalline waxes or synthetic waxes.

The physical properties of a wax used as a solid solvent have a substantial impact on the formability of the resulting gel film. Brittle waxes produce brittle gels, firm waxes produce firm films, and soft, deformable waxes produce conformable films. Microcrystalline waxes generally have a higher molecular weight than normal paraffin waxes, the number of carbons being in the range of thirty to above eighty. Branched hydrocarbons predominate in microcrystalline waxes, the degree of branching is typically in the range of 70 to 100 percent. The polymeric diluents can be used for polyethylene and can be mixed with non-polymeric diluents. In pavement marking applications, the building material must be able to withstand temperatures above 60 ° C, on black asphalt pavement on hot summer days. Wax-based gels have been prone to develop a liquid exudation of some component of the wax at such temperatures. A preferred wax for the combination of the shaping ability of the gel and a high temperature behavior has been Allied AC1702, a synthetic polyethylene wax supplied by Allied Chemical Company. At high temperature, however, the gels containing this wax will exude the smooth wax itself. The addition of a polymer component such as EPDM rr to the diluent can alleviate this problem. There are several ways to make the microporous base sheet. One type of process can be called thermally induced microporous phase separation, of which there are two types. One represented by U.S. Patent No. 4,539,256 (Shipman) in which the phase separation depends on the crystallization of the thermoplastic polymer; and one represented by U.S. Patent No. 4,519,909 (Castro) in which the phase separation depends on the differences in solubility between the polymer and the diluent at different temperatures. A second type of process can be called geltrusion or gel process. In general, the thermoplastic polymer (typically one of unusually high molecular weight, which is difficult to process by conventional melting processes) is made microporous primarily by heating it together with the diluent (e.g., mineral oil) to a temperature and for a sufficient time to form a solution (with lower viscosity than the pure polymer melt). The solution is formed into a desired shape (e.g., by extrusion) and then cooled (below crystallization or melting temperature) in said form at a sufficient rate and temperature so that phase separation occurs between the diluent and the polymer (for example, by shutting down the discharge of an extruder). Contrary to precipitation from a diluted solution, in the gel process a residual degree of molecular entanglement binds the polymer crystallites (in the case of crystallizable polymers) together within a gel, in which the diluent is maintained loose. If the quenching or cooling is fast enough, the degree of entanglement in the solution is retained in the gel as it solidifies. The cooling is continued until a solid results. When this type of conformation layer is used in articles such as those illustrated in Figures 6 and 7, a smaller portion of the diluent (e.g., by extraction, compression or evaporation) can be removed from the solid. Microporous thermoplastic sheets with a smaller portion of extracted diluent will be advantageous in applications in which porosity is desired, or in which the film has to be easily compressible or reduced in thickness. However, a major portion of the diluent must remain in the constructions as illustrated in Figures 6 and 7, so that the protuberances are not too deformable. As previously established, the conformational capacity can be empirically tested using simple methods. For articles of the invention that employ the microporous thermoplastic forming layers, a simple test is to press the material with the hand against a complete, rough or textured surface, such as a concrete block or asphalt pavement, remove it and observe the degree to which surface roughness characteristics are replicated in the material. Elastic recovery can be measured by observing the replicated rugosity trend, to disappear over time. A more quantitative measure of non-elastic deformation is performed in the following sequence: 1. A test strip (standard strip size for the tensile strength test) is pulled into a tensile strength device (eg, at a rate of 300% / minute), until it has stretched a predetermined amount, for example, 15%. 2. The deformation is reversed, causing a decrease in the tensile strength to zero. 3. In the repeated tensile strain, no force is observed until the sample is again tense. 4. The tension at which the force is first observed in a second pull is a measure of how much of the first deformation was present. 5. This tension divided by the first (for example, 15%) deformation, is defined as the non-elastic deformation (ID). A perfectly elastic material or rubber would have a 0% ID. The conformable materials useful in the present invention combine low strain strain and ID greater than 25%, preferably 35%, more preferably greater than 50%.

III. Magnetic particles The most likely choice of magnetic material is a particle composite of a permanent magneto material dispersed in a matrix of an organic binder. Many types of magnetic particles capable of being remotely magnetized, are known by those familiar with the technique of magnetic materials. The length of the principal axis of such particles (defined as the maximum length in any direction) suitable for use in this invention is in the range of about 1 millimeter (1000 micrometer) to about 10 nanometers (0.01 micrometer). The preferred range is from about 200 microns to about 0.1 microns. The saturation magnetization of the magnetic particles can be in the range of about 10 to about 250 emu / g (electromagnetic units / gram), and is preferably greater than 50 emu / g. The coercivity of such particles may be in the range of from about 100 to about 20,000 persons, more preferably in the range of from about 200 to about 5,000 persons. Particles with coercivities less than about 200 oersteds are too easily accidentally demagnetized, while particles with coercivities greater than 5000 oerstedios require relatively expensive equipment to be completely magnetized.

One class of high-performance permanent magnet particles are the rare earth metals alloy type materials. Examples of the incorporation of such particles in a polymeric binder include U.S. Patent No. 4,497,722, which discloses the use of samarium-cobalt alloy particles, and European Patent Application No. 260,870, which discloses the use of particles of neodymium-iron-boron alloy. Such particles are not the most preferred for this application, for the following reasons: 1) the alloys are relatively expensive, 2) the alloys can undergo excessive corrosion under conditions of prolonged exposure to the weather, and 3) the coercivity of such alloys is typically more than 5000 people. Many other types of permanent magnet particles of metal or metal alloy are available or could be produced. These include Alnico (aluminum-nickel-cobalt-iron alloy), iron, iron-carbon, iron-cobalt, iron-cobalt-chromium, iron-cobalt-molybdenum, iron-cobalt-vanadium, copper-nickel-iron, manganese -bismuth, manganese-aluminum, and cobalt-platinum. All materials of this type could be used, but these are not the most preferred. The most preferred magnetic materials are from the class of stable magnetic oxide materials known as magnetic ferrites. A particularly preferred material is the hexagonal phase of the magnetoplumbite structure, commonly known as barium hexaferrite, which is generally produced as flat hexagonal plates. Strontium and lead can partially or completely replace barium, and many other elements can partially replace iron. Strontium hexaferrite is also a preferred material. Another class of preferred materials are cubic ferrites, which are sometimes produced as cubic particles, but more often are needle-like, or needle-like, elongated particles. Examples include magnetite (Fe ^ 04), maguey or gamma-ferric oxide (gamma-Fe203), intermediates of these two compounds, and cobalt-substituted modifications of the two compounds or their intermediates. All these magnetic ferrites are produced in large quantities at relatively low cost and are stable under conditions of prolonged exposure to the weather. Their coercivities fall in the most preferred range of 200 to 5000 people. Chromium dioxide is another alternative material that may be useful as a magnetic particle in the invention, due to its low Curie temperature, which facilitates the magnetization methods termanemanente. The magnetic particles are generally dispersed in the polymer matrix at a high load, typically constituting at least 1 volume per cent of the magnetic layer. It is difficult to include particles in an amount that constitutes more than about 75 percent by volume of the material. A preferred loading range could be from about 30 to 60 percent by volume, more preferably from about 45 to about 55 percent by volume. To obtain the highest magnetic forces, the particles must be anisotropic particles substantially of size in the domain, and there must be substantially parallel alignment of the preferred magnetic axes, of a sufficient number of the particles to make the magnetic material itself, anisotropic .

The mechanical process described in U.S. Patent Nos. 2,999,275 and 3,359,152 for working the particle-loaded matrix material are preferred to provide the high degree of magnetic orientation. Ferrites, especially barium ferrite but also lead and strontium ferrites, generally in an approximately platelet-like form, having preferred magnetic axes perpendicular to the general planes of the plates, are preferred as particulate materials, but others Materials that have permanent magnetic properties, such as iron oxide particles or such as manganese-bismuth particles or iron protected against oxidation, can also be used. After mixing, the ingredients are processed on calendering or extruded rolls where they form a smooth band and are processed into thin sheets of the desired thickness. In general, the. The sheets are formed having a thickness of at least about a millimeter, and preferably at least about 1 millimeter, but in general the sheets are less than about 5 millimeters thick, and preferably less than 3 millimeters thick.

For coarse magnetic layers, a smaller volumetric charge of the magnetic particles can be employed. As previously indicated, the calendered sheet material is found to have a significantly higher tensile strength in the downstream direction of the net than it has in the direction transverse to the net, for example its downward tensile strength. the network is at least about 20 to about 25% greater than its tensile strength in the transverse direction to the network, and is desirable for ease of processing and for ease of application, but lower tensile strength in the direction Transverse to the network can allow the sheet material to have better conformability to the surface of a road. The magnetic layers of the invention generally have a downward tensile strength of the network of at least 10 kilograms per square centimeter at 25 ° C, and preferably at least 25 kilograms per square centimeter down the network. Three patterns of periodically reversible mangetization are possible. In the first, the direction of magnetization is perpendicular to the plane of the article. In the second, the direction of magnetization is in the transverse direction, or the width. In the third, the magnetization is in the longitudinal direction, or along. The best mode will be determined by an interaction of several factors, including: a) the best output signal for the determination and control of the position; b) the requirement of coercivity for the magnetic powder; c) the ease of orientation of the axis of the magnetic crystals in the direction of the magnetization, in order to obtain the maximum output or efficiency; and d) the magnetisation ease of the strip in the preferred direction.

IV. Non Magnetic Fillers Non-magnetic fillers are generally included in the composition, at least to color it, but preferably also to add other desired properties such as reinforcement, extension, surface hardness, and abradability. Plate fillers, for example, fillers having a plate-like shape, such as magnesium silicate, talc, or mica, are preferred, because they have been found to give the best resistance to abradability and strength properties with downward direction of the network. In addition, plate-shaped fillers have a high ratio of surface area to volume, which improves their reinforcing ability. Other non-magnetic fillers, such as needle-type or dial-type fillers, may be included in addition to the magnetic fillers, but only to the extent that they do not affect the ability to orient the easy magnetization axis of the magnetic particles, as desired . Other optional ingredients may also be included in the sheet material of the invention, such as UV absorbers, pigments and various additives.

V. Adhesives The adhesive layer on the bottom of the sheet material of the invention is preferably a pressure sensitive adhesive (PSA) such that the sheet material can be pressed against a road and removably adhered to it, although they can be employed Many types of adhesives, chemical and mechanical. The adhesive layer must provide at least 0.2 kilograms of adhesion per centimeter of width, and preferably at least 0.5 kilograms of adhesion per centimeter of width, in one. Release test at 180 ° C as described in ASTM D1000, paragraphs 36-38. A steel panel is used in this test as a standard panel to which adhesion is measured. Suitable pressure sensitive adhesives include rubber resin adhesives as shown in Freeman, U.S. Patent No. 3,451,537, and acrylate copolymers are shown in Ulrich, U.S. Patent No. Re. 24,906. The layer 8 is preferably from about 0.038 cm to about 0.051 cm (5 to 20 mils) thick. Useful adhesives include sticky pressure sensitive adhesives. PSAs are typically and preferably sticky in an aggressive and permanent manner at room temperature, adhere to substrates without the need for more than manual pressure, and do not require activation by water, solvent or heat. The PSAs useful in the present invention are selected from the group consisting of alkyl acrylate polymers and copolymers; copolymers of alkyl acrylates with acrylic acid; terpolymers of alkyl acrylates, acrylic acid, and vinyl lactates; polymers and copolymers of alkyl vinyl ether; polyisoalkylenes; polyalkyldienes; Alkyldiene-styrene copolymers; block copolymers of styrene-isoprene-styrene; polydialkylsiloxane; polyalkylphenylsioxanoxanes; natural rubbers; synthetic rubbers; chlorinated rubbers; crepe gum; turpentine resin; coumarone resins; Alkyd polymers; and polyacrylate esters and mixtures thereof.

Examples include polyisobutylenes, polybutadienes or butadiene-styrene copolymers, and mixtures thereof (such polymers and copolymers preferably do not have reactive portions, eg, do not oxidize in the presence of air); silicone-based compounds such as polydimethylsiloxane, and polymethylphenylsilpxane combined with other resins and / or oils. Useful PSAs also include thickened thermoplastic resins and thickened thermoplastic elastomers, wherein the thickener comprises one or more compounds that increase the tackiness of the composition. An example of a thickened thermoplastic resin, useful as aggressively sticky PSA, is the combination of a vinyl acetate / ethylene copolymer known under the trade designation VYNATHENE EY 902-30 (available from Quantum Chemicals, Cincinnati, Ohio) with substantially equal portions. of thickeners known under the trade designations PICCOTEX LC (a water-white thermoplastic resin produced by copolymerization of vinyltoluene and alpha-methylstyrene monomers having a ring and ring softening point of about 87-95 ° C, available from Hercules Incorporated , Wilmington, Delaware) and WINGTACK 10 (a liquid aliphatic hydrocarbon resin of 5 carbon atoms, available from Goodyear Chemical) and an organic solvent such as toluene. An example of a thickened thermoplastic elastomer, useful as an aggressively tacky PSA, is the combination of the styrene block copolymer, poly (ethylene-butylene) -styrene, known under the commercial designation KRATON G1657 (available from Shell Chemicals) with one or more than the low molecular weight hydrocarbon resins known under the trade designation REGALREZ (from Hercules) and an organic solvent such as toluene. These two formulations can be coated using an air-dried blades coater, or air dried followed by oven drying. Of course, the invention is not limited to the use of these specific combinations of thermoplastic resins, thermoplastic elastomers and thickeners. A preferred subclass of PSAs, due to their prolonged shelf life and resistance to the disappearance of stickiness under atmospheric conditions, are acrylic based copolymer adhesives as described in U.S. Patent No. Re. 24,906. An example of such an acrylic-based copolymer is a copolymer of isoctyl acrylate / acrylic acid 95.5: 4.5 (measured in parts by weight each). Another preferred adhesive is the copolymer of a combination with a weight ratio of 90:10, of these two monomers. Other preferred adhesives are the terpolymers of ethyl acrylate, butyl acrylate, and acrylic acid; the copolymers of isooctyl acrylate and acrylamide; and the terpolymers of isooctyl acrylate, vinyl acetate, and acrylic acid.

The sticky acrylic PSAs useful in the invention may be covered with a coating composition comprising an organic solvent, such as a solvent mixture of heptane: isopropanol, and the solvent is subsequently evaporated, leaving a pressure sensitive adhesive coating. The layer 8 is preferably about 0.038 centimeters (cm) to about 0.11 cm (5 to 15 mils) thick when the substrate is a retroreflective sheet material. Polyorganosiloxane PSAs can also be used. Suitable silicone PSAs are those that exhibit pressure-sensitive behavior at temperatures of 0 ° to 50 ° C, which have improved impact properties, and which form adhesive bonds at low temperatures when compared to PSAs, which have been conventionally used in pavement marking tapes. The preferred polyorganosiloxane PSAs make possible the effective application and adhesion of the tapes to road surfaces, at significantly lower temperatures than those previously accepted as standards for the application of road marking tape. However, the low temperature advantage of this invention can only be fully available when used in conjunction with pavement marking sheets (such as foils) which also remain flexible and conformable at low temperature Suitable silicone PSAs, when coated as a 76 micron (3 mil) thick polyester liner, are characterized by a 90 ° peel strength from about 1.8 to about 10.5 NT per cm (about 1.0 to about 6.0 pounds per inch in width) of stainless steel at a peel rate of 54 cm (21.4 inches) per minute at 21 ° C, and the peel strength is greater than 0.4 NT per cm of width (0.25 pounds per inch of width) when tested at 2 ° C. When the previous peel tests are performed, the sample is laminated to a stainless steel panel using two passes of a 3.8 cm (1.5 inch) diameter roll of hard rubber (70 shore A durometer) and 2.27 kg (5 pounds) of pressure. A residence time (typically 5 minutes) is allowed before detachment. The low temperature test is carried out in a cold room at 2 ° C and all the equipment and material is at 2 ° C, so that application, residence and removal occur at low temperature. Appropriate silicone PSAs, when coated as a layer of 76 microns (3 mils) thick on the 51 micron (2 mils) thick polyester reinforcement network, are characterized by an adhesive tension in the cylinder twin (as taught in U.S. Patent No. 5,310,278), for 54 cm per minute (21.4 inches per minute) of pull speed in a standard tensile strength measuring device, of at least about 1.3 NT per cm width (0.75 pounds per inch width) at 21 ° C and at least about 0.8 NT per cm width (0.5 pounds per inch width) when measured at 2 ° C.

SAW. Manufacturing Methods In embodiments exemplifying styrene- or acrylonitrile-butadiene rubbers and the like, traditional rubber processing methods will likely be used to produce the conformable magnetic layer, which may also include the functionality of the other layers.

Typically, the composition is made in some type of heavy duty, batch or continuous, rubber kneading machine, such as the Banbury mixer or the twin screw extruder. The magnetic layer 2 can be formed by calendering between heavy rollers and then dividing it to the desired width, directly by extrusion through a die, or by a combination of such methods. If the extruded material is semi-liquid as it exits the die, the desired orientation of the magnetic particles in the desired direction can be achieved in one of many ways at the exit of the die, through the use of an electromagnet or permanent magnet. If the extruded material is more rubber-like than liquid, the magnetic orientation can not be successful, but the orientation could be achieved by mechanical work. The plate-shaped particles, such as barium hexaferrite, will respond to mechanical work by orienting with their planes in the plane of the sheet. Since the preferred magnetic direction for such particles is perpendicular to the plane, the preferred direction of the magnetization of the articles of the invention will be perpendicular. The needle-shaped particles will tend to align with their longitudinal axis in the plane. Since the largest magnetic axis corresponds to the axis of the needle, the preferred direction of magnetization for an article containing such particles is transverse or longitudinal. The flow in extension, such as occurs during extrusion, will promote the longitudinal orientation at the expense of the transverse orientation.

VII. Installation Methods The magnetic articles of the present invention can be installed in the form of tapes on a road, or other site, using any of a variety of devices such as human-pushable jets, types of jets "behind a truck", and "integral on a truck" type jets. U.S. Patent No. 4,030,958 (Stenemann) describes a type jet behind a suitable truck, for the application of the articles of the invention in the form of tapes reinforced with adhesive, to the. surface. This device includes: a. an structure; b. a support on the structure for rotatably supporting a roll of said belt; c. an application head for applying the belt to the paved surface comprising: i) a coupling roller that is movable toward and away from the paved surface; ii) the security means for maintaining the tape adjacent to the coupling roller, such that the movement of the coupling roller to the paved surface presses the tape into engagement with the paved surface; iii) a pressure roller to press the tape after it has been engaged against the paved surface, by means of the coupling roller; and iv) the cutting means for cutting the tape extending between the coupling roller and the pressure roller, after the coupling roller has been moved away from the paved surface; d. the accumulator means located between the tape roll and the application head, and comprising a group of guides on which the tape is wound, said guides being movable against an adjustable deviation pressure, from a first position which provides a way in coil for the tape traveling from the tape roll to the application head, at least to a second position that provides a more direct path for the tape; and. the chronometer means for initiating the movement of said roller towards and away from the paved surface; and f. the starting means of the belt, operable by the means of the chronometer before the movement of the coupling roller to the paved surface, and comprising the means for relaxing the diverting pressure on the accumulator, to allow easier movement of the accumulator from the first position to the second position. The tape extends in a continuous length through the apparatus from the supply roll to the coupling roller, and the tape is under pressure over that length. Another application of the tape proceeds smoothly, without shaking or tearing the tape. The tape is maintained under positive control throughout the operation, such that the straight lines and desired spacing are reliably adhered to the paved surface, and the strips can be applied quickly in an automatic tape laying operation on the road. . Other means may be used to install the articles of the invention, such as the simple manual application, or the use of the previously mentioned mechanical fasteners.

VII. Mobile Objects Guide Systems As previously stated, the invention also comprises a system for guiding a moving object on a road, through a warehouse, and the like. The primary components of the systems of the invention are the conformable magnetic articles of the invention, at least one sensor for detecting the magnetic field coming from the article, and an indicator that receives a signal from the sensor, to alert or warn of the moving object. A typical lateral position indicating system of the invention, suitable for use in the guidance of a vehicle operated by a human, is illustrated in Figure 8 (without the article of the invention).

A. Sensors A number of sensors and transducers are available to convert the magnetic signal coming from the articles of the invention to an electric voltage or current appropriate for the additional processing of the signal. Flow composite magnetometers are highly sensitive, but they can be too slow and expensive for this application. Hall effect sensors are fast, compact and cheap, but probably not sensitive enough. Recently, economic solid-state (MR) magnetoresistive sensors have become available, which can quickly and accurately measure fields below 10 milligaus (with a sensitivity of less than 0.01 milligaus) while consuming less of 1 milliwatt of energy, such as those described in U.S. Patent Nos. 4,634,977 and 4,742,300. There is a potential problem in distinguishing the guide signal from "magnetic noise" produced by steel reinforcing bars, other vehicles, and the like. A signal of 10 milligaus is small compared to the magnetic field of the earth of approximately 500 milligaus. However, if the article of the invention is • magnetized in a regular alternating pattern, the magnetic signal will then be periodic with a frequency proportional to the speed of the vehicle. Modern signal processing techniques can then be used to extract the signal at a known frequency from the noise. The complete specification of the magnetic field at any point in space requires the detection of the field components in three mutually orthogonal directions. The magnetic sensors coupled to the vehicle can determine the field in one, two or all three directions. A mathematical combination of two or three field components can be used to compute a signal that can be related to the lateral distance of a vehicle from the articles of the invention. A device and method useful in the present invention for determining the scopes and markings in a plane of an object characterized by a magnetic dipole, is described in U.S. Patent No. 4,600,883 (Egli et al.). This patent describes a method for the determination, with a device to measure the perturbations of the magnetic field, the marking? of a ferromagnetic material located in a region subject to an external magnetic field of known force and direction within the region, where? is the angle between a line coming from the measuring device towards the site of the ferromagnetic material in a first direction, the first direction being the direction of the external magnetic field at the site of the ferromagnetic material, comprising: the determination of a first component of the perturbation of the external magnetic field at the site of the device of the invention along the first direction, determining a second component of the perturbation of the external magnetic field at the site of the measuring device along a direction orthogonal to the first direction , and that lies in the plane, forming a first equation by adjusting the first component equal to (3cos2? -1), forming a second equation by adjusting the second component equal to (3cos? sin?), forming a ratio of The first and second equations by which a third equation is produced, and determined? from the third equation. An apparatus described for the completion of the method includes a two-axis agnetometer and a computer (which typically includes an average or main memory containing undisturbed values of the components of the magnetic field, a subtractor to subtract the undisturbed value from the perturbed values of the components of the magnetic field in the planes, and various generators and parameter determiners ). A method suggested in U.S. Patent No. 4,600,833 includes the use of the computer for computing? using an iterative process.

B. Media Indicators Preferred indicating means include at least one horn, calibrator, beep, electric shock, LCD, CRT, light, combination of these and the like. One or more indicator means may be desired in a particular situation.

And emplos The articles and systems of the invention are further explained in relation to the following examples, in which all the parts and percentages are in ppso, a. not to be specified otherwise.

The following materials were used in the examples.

Paracril® B a nitrile rubber medium containing acrylonitrile, available from Uniroyal Chemical Company of Akron, Ohio Chlorez® 700S a solid chlorinated paraffin available from Dover Chemical Corporation of Dover, Ohio Paroil 140 LV a liquid chlorinated paraffin available from Dover Chemical Corporation of Dover, Ohio PE NA249 a low density polyethylene, available from Quantum Chemical Corporation, Emery Division of Cincinnati, Ohio Stearic Acid a process assistant available from Hu ko Chemical Division of Witco Chemical Corporation of Memphis, Tennessee Vanstay® SC a "chelating agent" stabilizer available from R.T Vanderbilt Company, Incorporated of Norwalk, Connecticut Santowhite® Crystals an antioxidant available from Monsanto Chemical Company of Saint Louis Missouri Mistron® Superfrost a talc available from Luzenac America, Incorporated of Englewood Colorado HiSil® 233 an amorphous hydrous silica available from PPG Industries, Incorporated, of Pittsburgh Pennsylvania PE Minifiber 13038F a high density polyethylene fiber available from Mini Fibers, Incorporated Johnson City, Tennessee Fibers PET 6-3025 a 6.35 mm polyester fiber by 3 d (1/4 inch by 3 d) available from Mini Fibers, Incorporated of Johnson City, Tennessee Bario Hexaferrite P-235 a magnetic pigment available from Arnold Engineering Company of Norfolk, Nebraska Example 1 A test strip was developed by laminating a 10.2 x 0.15 cm (4.0 x 0.060 inch) pavement marking tape known under the trade designation SCOTCHLANE Series 620, available from the Minnesota Mining and Manufacturing Company, Saint Paul, MN (" 3M ") for a commercially available flexible magnetic material of the same width and thickness, known under the trade designation PLASTIFORMT Type B-1033 flexible magnetic strip, produced by Arnold Engineering, Norfolk, Nebraska. Material B-1033 consisted of perpendicularly oriented barium ferrite particles in a nitrile rubber binder with a remaining magnetization (Br) of approximately 2500 gauss. The orientation of the barium ferrite was achieved by a mechanical calendering process (the product was purchased from Arnold Engineering already calendered). A roll of 10.2 cm wide material, completely magnetized through the 0.15 cm thickness, was cut into sections each having a length of about 61 cm, with each of the other sections inverted to give an alternating field pattern. The strips were then laminated to the bottom of a continuous section of the pavement marking tape. An adhesive was coated on the underside of the laminated strip to facilitate coupling to a test section of the asphalt road. The material of the invention was placed in the center of the rail, so that a magnetometer mounted in the center of the front bumper of a vehicle could be directly on the magnetic strip material. The MR sensors were then driven along the strip at a fixed height of approximately 23 cm, and the profile of the magnetic field was recorded. One was mounted a video camera such that. a t register of the effective lateral displacement to the magnetic strip could be made, to allow a comparison of computed (magnetic) shift to cash (video). Inside the vehicle, a data acquisition system was used to record the 3 axes of the magnetometer outputs, as well as a synchronization signal from the video system. A total of 23 runs were made. Different maneuvers were carried out to guide the path of the sensors on the magnetic strip in various ways, including directly above and parallel to the straight line transverse, parallel, displaced and the shapes in "S". The analysis of the data proved extreme positivity. While it was expected that the articles of the invention could be limited to a lateral displacement of approximately 30 cm, it was unexpectedly found that the signal from the test strip was discernible at a distance of up to 1.83 m (6 feet). In addition, when the lateral displacement computed by the data acquisition system (magnetic) was plotted against the displacement shown by the true ground, video system, the line is almost straight at 45 °, where a straight line, at 45 ° represents a perfect correlation.

Example 2 For this MPMT example, instead of two layers plus one adhesive layer as in Example 1, a single layer plus the adhesive construction will be employed. The magnetic powder takes the place of some or all of the filler material in a marking tape formulation for pavement such as that described in U.S. Patent No. 4,490,432. The designed experiments will be used to optimize the formulation. This formulation will have conformability and magnetic operation requirements, but will not have appearance requirements. The dark color given by the pole will be acceptable. Since it is not desirable to cut the strip, a method for magnetizing it in an alternating pattern while still being in the form of a continuous strip is highly preferred. If a perpendicular direction of magnetization is chosen, the strip can be run between the iron pole pieces of an electromagnet, periodically inverting the direction of the current to reverse the direction of magnetization.

Examples 3-15 A formulation experiment was carried out to study the effects of magnetic particle loading on the magnetic and physical characteristics of the conformable magnetic sheet articles of the invention. These experiments showed the utility of replacing all or some of the inorganic fillers, conventional pavement marking sheet materials, conformable, non-magnetic, with magnetic particles. Tables 1 and 2 show the formulations of some exemplary conformable magnetic sheet compositions useful in the articles of the invention. The formulations of Examples 3 to 6 were made with the magnetic particle charges at 30, 40, 50 and 60 percent by volume. The formulations of Examples 7 to 9 were made with magnetic particle charges at 30, 40, and 50 percent by volume. The components of the master batch of each formula were composed in an internal material type Banbury to intimately mix the ingredients. The mixture was then zunchada on a rollers rubber roller. The magnetic particles were added to the compound bonded on the mill. After the addition of the magnetic particles, the composite mixture was converted to sheet with the laminator to a thickness of approximately 1.3 mm. The magnetic properties of the articles of the examples were measured using a vibratory sample magnetometer manufactured by Digital Measurement Systems, Cambridge, Massachusetts. Based on these measurements, the magnetic properties of these sheet materials were in an acceptable range for use as a magnetic conformable sheet with magnetic particle content of 30 to 60 percent by volume. The contents of magnetic particles in the range of 45 to 55 percent by volume appeared particularly useful because of their acceptable magnetic properties and their potential for further optimization of the physical characteristics of the sheets, through the use of other fillers and modifiers. Examples 10 to 15 further illustrate the substitution utility of only some of. inorganic fillers in sheet materials for marking pavement, conformable, non-magnetic, conventional, with magnetic particles at a load of 50 percent by volume of magnetic particles. These materials were composed in a manner similar to those of Examples 3 to 9, using an internal Banbury-type mixer to mix the master batch portion of the formula, and adding the magnetic particles and forming a sheet on a two-roll rubber laminator. . The magnetic properties were in the ranges expected for a composition that had a 50 percent volume loading of magnetic particles. Physical characteristics such as manual and tensile properties were at intervals similar to those shown by conventional sheet materials for marking pavement, conformable, non-magnetic. In addition, the sheet of Example 12 had "manual" characteristic of the conformable sheets made according to the US patent No. 4,117,192. The engraving ability of the sheets of Examples 13, 14 and 15 was shown using a patterned platen having the pattern of US Patent Nos. 4,388,359 (Ethen) and 4,988,541 (Hedblom) in a platen press at temperatures of 125 ° at 150 ° C (250 ° F to 300 ° F) loaded with 10 tons (9,080 kg) of applied pressure over a leaf area of approximately 150 cm2 for a period of 2 to 4 minutes. The engraved sheets of the Examples 13 and 14 had a manual characteristic that suggested particularly good utility in the production of magnetically modified constructions, similar to those of U.S. Patent No. 4,988,541 (Hedblom). Based on these rough tests, it is expected that the materials of Examples 10-15 will probably show 65% or less of creep recovery in the Sengupta conformability test mentioned in the section II A above, and greater than about 25% of the non-elastic deformation in the non-elastic deformation test mentioned in section II C above.

Examples 16-18 are examples of longitudinally divided pavement markings of the types described in Figure 7.

Example 16 An article of the invention could be made using processes similar to those used to produce pavement markings known under the trade designation STAMARK Contrast Tape 380-5 (a white pavement marking tape having longitudinally spliced black material at each edge of the material white to provide improved visual contrast and marking visibility, available from 3M) to produce a magnetically modified contrast ribbon that provides a detectable magnetic signal and improved visibility. A continuous roll of STAMARK Series 380 pavement marking tape (also available from 3M) could be longitudinally spliced to a second continuous roll of an engraved magnetic sheet, coated with adhesive, of composition similar to that of Example 12 above, using a fiberglass cloth tape which is fully coated, having a sensitive adhesive. pressure on both sides, for example, the tape known under the trade designation SCOTCH Glass Cloth Butt Splicing Tape DCX (available from 3M), to join the two rolls on its edge with the splice tape adhered to the outer surface of the STAMARK Series 380 marking tape and engraved magnetic sheet, coated with adhesive of the present invention.

Example 17 (Modality of Figure 7) An article of the invention could be made by using the same process used to produce Example 16, with the additional step of providing a longitudinal splice of the engraved magnetic sheet, coated with adhesive, of the invention, to both minor edges of the invention. STAMARK® series marking tape for Series 380, to provide two regions of visual contrast to the article. This is the modality illustrated in Figure 7.

Example 18 An article of the invention could be made using the same steps used to produce Example 17, with the exception that instead of a second recorded magnetic sheet strip, a strip of the known tape could be used under the trade designation STAMARK 385 Series Non-Reflective Joint Cover Tape (a black pavement marking tape available from 3M), to provide two regions of visual contrast to the article, one magnetic and one non-magnetic. Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes in form and detail may be made without departing from the spirit and scope of the invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (10)

1. An article comprising a conformable magnetic layer, characterized in that it comprises: a) an organic binder comprised of organic materials selected from the group consisting of non-crosslinked elastomeric precursors, thermoplastic polymers, and combinations thereof; b) at least 30 percent by volume of magnetic particles distributed in said organic binder, the magnetic particles are capable of being remotely magnetized to produce a magnetic field sufficient to be detected by a sensor.

2. The article according to claim 1, characterized in that the article is a magnetic tape having first and second main surfaces comprising: a) a magnetic conformable magnetic layer comprising the binder and magnetic particles, wherein the magnetic particles are capable of be remotely magnetized to produce a magnetic flux of at least 10 milligauss at a distance in the range of about 15 to about 30 cm from a center of the tape; and b) a layer of adhesive adhered to a larger surface of the article.

3. The article according to claim 2, characterized in that the second major surface of the magnetic layer has an elastic support layer adhered to it, the elastic support layer serves to join a plurality of retroreflective elements thereto.

4. The article according to claim 2, characterized in that at least one of the magnetic layer or the adhesive layer has a fibrous network material embedded therein.

5. The article according to claim 2, characterized in that the conformable magnetic layer has: a) a front surface; b) a plurality of integral protuberances projecting from the front surface, there being a plurality of such protrusions across the width and below the length of the article, each of the protuberances having an upper surface and at least one lateral surface connecting the upper surface to the front surface of the shaping layer .; c) a first discontinuous splice joining layer covering a selected group of surfaces of the projections; and d) a first plurality of particles partially embedded in the first joining layer, and projecting partially from the first layer of the splice junction.

6. The article according to claim 2, characterized in that the magnetic layer is comprised of perpendicularly oriented barium ferrite particles in a nitrile rubber binder with a remaining magnetization (Br) of approximately 2500 gauss.

7. A control and guidance system for mobile, magnetic objects, characterized in that it comprises: a) al. minus a conformable magnetic article according to claim 1; and b) a sensor that detects the magnetic field produced by the magnetic article.

8. The article according to claim 1, further characterized by at least one of the following: a) the magnetic particles comprise up to about 75 percent by volume of said layer; or b) the magnetic particles comprise up to about 60 percent by volume of said layer.

9. The article according to claim 1, characterized in that the magnetic particles comprise up to about 95 percent by weight of the layer.

10. The article according to claim 1, further characterized by at least one of the following: a) the magnetic particles are oriented; or b) the magnetic particles have a saturation magnetization in the range of about 10 to about 250 emu / g and coercivity in the range of about 100 to about 20,000 oersteds.